Field of the Invention
This invention relates to carriage and saw elements in sawmill operations and more particularly, to the cutting of curved logs along preselected curved saw paths by a pivotally-mounted band saw and pivoting carriage operated manually or by a computerized control system. In a first preferred embodiment the band saw and carriage are pivotally mounted and coupled to interfacing programmable logic controller equipment and an associated scanner/computer, to facilitate optimum selection and control of desired blade paths through a curved log and optimizing the wood products from the log. In a second preferred embodiment of the invention a computer is provided in association with the programmable logic controller to receive data from the scanner/computer and a carriage location encoder and operate the programmable logic controller to effect the desired cutting path or paths through each log. The manually or computer-operated programmable logic controller is linked to linear positioners mounted on corresponding fluid-operated cylinders provided on both the band saw and the carriage, as well as the log-positioning knees on the carriage, for securing the respective logs on the carriage, orchestrating pivoting of the band saw on a fixed band saw base and the carriage on a linear-travelling trolley and facilitating the desired optimum cut(s) through the log.
In sawmill operations it is sometimes desirable to cut a curved log approximately along the line of curvature inwardly of the concave bark layer to produce lumber of optimum selection, grade and quality. This technique is impossible under ordinary circumstances using either a band saw or circular saw, because conventional carriages which carry the logs are normally operated in a linear fashion to force the logs into the blade of the corresponding band saw or circular saw along a straight line and effect the desired linear cut. Since the carriages operate in a straight line, cuts through the logs are normally also straight. Accordingly, there is normally no effort made to cut a curved or crooked log according to its natural curvature in order to realize lumber of optimum quality and selection from the log.
It is an object of this invention to provide a pivoting carriage and saw for cutting both straight and curved logs, wherein the pivoting carriage is pivotally adapted to maneuver the log into the path of a pivotally-mounted band saw blade throughout the length of the log, to facilitate cutting the log in a selected path.
Another object of this invention is to provide a new and improved pivoting carriage and band saw system for cutting curved logs along a selected curved path, which system includes a pivoting carriage mounted on a linear-operated trolley and adapted to receive and support a log, a pivoting band saw mounted on a fixed base or band mill located adjacent to the trolley and carriage, a scanner/computer for determining the optimum cutting path or paths for the band saw to optimize the wood products from the log and a programmable logic controller coupled to linear positioners mounted on fluid-operated cylinders provided on the carriage and band saw, wherein the carriage and band saw may be pivoted in concert by operation of the programmable logic controller to cut the log according to selected curved paths determined by the scanner/computer and optimize the wood products from the log.
Still another object of this invention is to provide a new and improved pivoting carriage and band saw assembly for sawmills, which assembly includes a pivotally-mounted carriage mounted on a linearly-operated trolley and adapted for receiving, supporting and positioning a curved log by use of sliding log-positioning knees, a band saw pivotally mounted on a fixed base adjacent to the carriage, a scanner/computer positioned to select an optimum cutting path or paths through the log and a computer-operated programmable logic controller system coupled to the scanner/computer and to linear positioners mounted on fluid-operated cylinders provided on the log-positioning knees, pivoting carriage and pivoting saw, for locating a log in proper position on the carriage, orchestrating pivoting movement of the carriage and saw according to scanned parameters of the log and cutting selected, optimum curved paths through the log from end to end to optimize the size and selection of wood products from the log.
A still further object of this invention is to provide a method for cutting a curved log and increasing the yield of wood products of optimum size and selection from the log, which method includes the steps of securing the log on a pivoting carriage in the path of a pivoting band saw scanning the log to determine optimum saw cuts through the log to produce lumber of optimum proportions and pivoting the carriage and band saw in concert by operation of a computerized control system to effect these saw cuts in the log.